#include <stdio.h>

void my_strcat(char *dest, const char *src)
{
    char *temp = dest;
    while (*temp != '\0')
        temp++;
    for( int i = 0; *src != '\0'; i++ , src++, temp++)
        *temp = *src;
    *temp = '\0';
}

void main()
{
    char str1[20] = "Hello";
    char str2[] = "World";
    my_strcat(str1, str2);
    printf("%s\n", str1);
}